There are, of course, a large number of conveyor and other feed systems which have been developed for various purposes including the feeding of product to packing machines. Many of these systems include relatively complex controls and, for example, employ computer activation and monitoring. Representative examples of relatively simple conveyor and like systems, and the controls therefor, are contained in U.S. Pat. Nos. 2,618,162 (Musschoot); 3,011,621 (Byrnes); 3,645,305 (Warlop); and 3,731,787 (Gregor). Characteristically, packaging machine control systems detect the feed conditions at each station and individually control the feed to that station accordingly. For example, in the Warlop patent, a photocell arrangement is employed to detect the "full" condition at each station and to control, responsive to detecting such a condition, the closing of a gate for the feed from a conveyor. Somewhat similarly, in the Gregor patent a photocell arrangement is used to sense the fill level at each machine and to activate upstream vibrators to complete filling to the full level.